1. The Nervous System chapter 37
Gathering, analyzing and responding to stimuli - information from internal and external environment - via nerve cells, aka neurons
All domains detect and respond; only animals have a NS

2. Neuron Circuitry a one-way loop
2) Interneurons in brain,
spinal cord analyse incoming
info, send msg to…
1) Receptors attached to
sensory neurons receive stimuli,
direct impulse to…
receptor
interneuron
3) Motor neurons to effectors for response
effector

3. Neurons interact chemically
Information travels down the axon as a charge (action potential) but breaches the gap between neurons chemically, via neurotransmitters
Direction of impulse
axon
Vesicles release neurotransmitters via exocytosis
dendrite
One dendrite can receive info from many axons

4. Reflex arc spinal cord directs response - msg to brain after the fact
message to brain
patellar reflex
Pain, blinking,, etc.
Interneuron in cord relays to motor neuron
moro reflex

5. 2 NS divisions CNS - central nervous system
brain, spinal cord
(+20 billion interneurons!)
PNS - peripheral nervous system
receptors, sensory neurons
effectors, motor neurons

6. Receptors photoreceptors mechanoreceptors nociceptors chemoreceptors
Attached to sensory neurons
photoreceptors
10 million sensory neurons!
mechanoreceptors
nociceptors
chemoreceptors

7. Effectors Terminal end of motor neurons muscles glands
Half million motor neurons!
muscles
glands

8. NS architecture PNS motor sensory CNS brain spinal cord autonomic
respond take in
brain
spinal cord
autonomic
somatic
Involuntary
internal stimuli
glands, heart, etc
Voluntary
external stimuili >
skeletal muscle
effector
Somatic, autonomic work
together to maintain
homeostasis
Exception; reflexes are somatic
Ex: as body temp drops, somatic causes shivering, autonomic constricts surface blood vessels
sympathetic
parasympathetic
‘rest & digest’
‘fight or flight’